1. Field of the Invention
This invention relates to an automatic body temperature adjuster and, more particularly, to an automatic body temperature controller for automatically controlling the temperature of a person who has lost his or her body temperature control function because of, for example, damage to the spinal cord.
2. Prior Art Statement
In a person who has lost his or her body temperature control function because of, for example, damage to the spinal cord, heat generated by metabolism is not sufficiently dissipated outside of the body when the ambient atmospheric temperature and/or relative humidity is high, such as in summer. In this case, the heat is retained in the body, leading to heat retention. In extreme cases, the heat retention may very seriously disrupt the physiological functions.
To prevent the heat retention, heat is forcibly extracted from the person's body. The usual practice is to put the person in an air conditioned room. However, in addition to being an expensive solution, this method confines the person to an air conditioned building or room.
Japanese Patent Public Disclosure Sho No. 61(1986)100243 discloses a mobile automatic body temperature adjuster which is denoted in FIG. 8 by the symbol Ca. As the adjuster is mobile, the user is not confined in any particular place.
This automatic body temperature adjuster Ca comprises a heat or cold storage material; a circulation means including a circulation pump, a supply section for supplying heat or cold to the heat or cold storage material and a receiving section for receiving heat or cold from a heat or cold source, which are connected to form a closed circuit for circulation of a medium from the receiving section to the supply section through the circulation pump; a sensor for sensing temperature of the heat or cold storage material; control means for producing a signal for controlling the amount of heat or cold received by the heat or cold receiving section according to a signal from the sensor; and a holding member for holding the heat or cold storage material and sensor in contact with the user's body and also holding the heat or cold supply section in contact with the heat or cold storage material.
As shown in FIG. 8, the aforementioned adjuster comprises a liquid cooler 9a which includes a DC compressor 6a, a condenser 7a, a capillary tube 8a and a heat exchanger 1a and serves as a cold source, a cold medium circulation path 30a which connects the heat exchanger 1a, a three-way valve 10a, a circulation pump 4a and a cold supply section 5a to form a closed circuit and also includes a bypass 31a bypassing the heat exchanger 1a and connecting with the remaining port of the three-way valve 10a, a controller 11a, a sensor 13a for sensing the temperature of the user's body, and a cold (heat) storage member 14a. The cold storage member 14a is filled with a cold storage material (e.g., an aqueous solution of sodium chloride). The individual components of the automatic body temperature adjuster Ca are driven by a rechargeable battery.
The liquid cooler 9a conducts a refrigerating cycle using a coolant gas medium. The coolant gas medium is compressed in the DC compressor 6a, causing it to be increased in temperature and pressure. It is then supplied to the condenser 7a to be cooled and liquefied. The liquefied coolant medium is passed through the capillary tube 8a for pressure reduction and is then supplied to the heat exchanger 1a where it evaporates, thus extracting heat from its surroundings and providing a cooling function.
Likewise, the heat exchanger 1a, the three-way valve 10a, the circulation pump 4a, the path of the cold supply section 5a and the bypass 31a constitute a coolant medium circulation path 30a using a liquid (e.g., water) as a coolant medium. The circulating coolant medium which has been cooled by the heat exchanger 1a passes through the three-way valve 10a and is supplied by the circulation pump 4a to the cold supply section 5a. As it circulates through the cold supply section 5a, it extracts heat from the body of the user whose body temperature is to be controlled. Then, part of it is circulated to the heat exchanger 1a and the remainder is circulated to the bypass 31a. By varying the ratio of the circulating coolant medium that is sent to the heat exchanger 1a for cooling to the medium that flows through the bypass 31a, it is possible to control the temperature of the circulating medium supplied from the three-way valve 10a to the cold supply section 5a. The controller 11a is constituted as a microcomputer. Based on a user body temperature signal produced by the sensor 13a, which is attached to a cover 12a worn by the user, the controller 11a produces a signal for controlling the three-way valve 10 to supply circulating medium at the optimum temperature to the cold supply section 5a. It also produces a signal for controlling the rotational rate of the DC compressor 6a to vary the cooling power of the heat exchanger 1a, i.e., the refrigeration capacity of the liquid cooler 9a. The cover 12a and the liquid cooler 9a of the automatic body temperature adjuster Ca are linked by a coupler (not shown). When the automatic body temperature adjuster is used outdoors, the liquid cooler 9a and the battery (not shown) used as a power source are mounted on a wheelchair.
As during outdoor use, the automatic body temperature adjuster Ca is powered by a battery mounted on a wheelchair, the automatic body temperature adjuster cannot be used outdoors continuously for more than a limited period which is determined by the battery capacity.
To overcome this limitation, it might be considered to use a battery having a large capacity. However, a battery with large capacity inevitably has increased size and weight. When such a large and heavy battery is mounted on a wheelchair, the wheelchair becomes impractically difficult to operate.